top of page

Japanese Beetles

       Japanese beetle (Popillia japonica) is a well known pest (green metallic armor with June bug shape) in the Midwest causing the disfiguration of trees and gardens. While small populations have a minimal effect on plant health, allowing a large population to develop may completely defoliate a tree leaving dead branches that lead to tree decline.

       Foliage is a requirement for photosynthate production. Reducing the foliage leads to less stored carbohydrates, to utilize through respiration, feeding biological growth.

       Large populations of Japanese Beetles in Des Moines will lead to weaker trees, tree decline, dead trees and an overall less vigorous tree population.

Is there a cure for a Japanese Beetle infestation?

No cure but we do have some great treatments that allow for acceptable reduction in Japanese Beetle populations.

       Insecticide trunk (basal) injection. Our leading product provides seasonal control of the Japanese Beetle.

       Advantage - you can treat prior to adult emergence and have protection through the entire season.

       Disadvantage - Some damage to plant from Japanese Beetle due being a slower working insecticide but the overall Japanese Beetle population will be reduced.

       Insecticide trunk (basal) injection. This secondary product is great for last minute reduction of Japanese Beetle population. Injected into the tree it stays active for only 30 days but packs a punch being called a “knockdown” insecticide. 

       Advantage - Kills the Japanese Beetle more quickly. 

       Disadvantage - is that it only stays in tree for 30 days and timing may be an issue.

Soil Treatments are warranted in only the most extreme cases to save a tree and are not a long term treatment viable in the reduction of Japanese Beetle Populations due to effect on soil biodiversity.       

Japanese Beetle populations

Japanese Beetle

Reduced Transpiration and Photosynthate production due to holes in leaves

Japanese Beetle Damage

       While the adult life cycle of the Japanese Beetle is over at the end of the growing season, it is always a good time to look ahead.

       Some of the most common trees to suffer dieback from the Japanese Beetle in Des Moines, Iowa are the River birch (Betula nigra), Paper birch (Betula papyrifera), Linden or American basswood (Tilia americana) and fruit trees. While many other trees are favored, these tend to have higher populations that may require pest management by Olson Tree Care.

What should you do to control the Japanese Beetle?

       - Some Tree Services believe that treating the soil, attempting to reduce the grub life of the Japanese Beetle, is the way to go. The Arborist at Olson Tree Care in Des Moines, Iowa has found this effort is not environmentally sound, nor effective. The population does not stay specific to the tree it emerges near. They migrate well to new locations meaning that reducing populations in the soil only reduces the number in whole for an area, not a tree specifically.

       - Spraying would be another futile endeavor. ISA Certified Arborist Treatments have very little residual effect and limited population control. (Not to mention the environmental impact of spraying insecticides.)

       - The best Tree Care Service we have seen on high value and high risk trees is trunk injection with Imidacloprid or Acephate. Acephate is a quick acting knockdown insecticide with a short residual while Imajet provides great seasonal control. When done in a timely manner, the tree will have a good 30 days to a full year of protection from the short life cycle of the adult Japanese Beetle.

bottom of page